FatSecret Premier API: Design Sprint Report

What We Did

We have a 30-day FatSecret Premier API trial starting 02 Apr 2026. This sprint designed the UI/UX for 6 features that the API unlocks, with one hard constraint: every feature must degrade gracefully when its feature flag is off. The app must never look broken.

This sprint produced interactive HTML/CSS prototypes for all 6 features (both ON and OFF states), a feature flag architecture spec, UX interaction notes, acceptance criteria, and a QA test checklist. No React code was changed.

Feature Overview

Flag Design

featureFlags: {
  fatsecret: {
    enabled: false,           // master switch
    barcodeEnrichment: false, // FS-001
    foodSearch: false,        // FS-002
    nutritionPanel: false,    // FS-003
    dietaryPreferences: false,// FS-004
    nutritionSummary: false,  // FS-005
    categoryInference: false, // FS-006
  }
}

Resolution logic:
  isEnabled(flag) => fatsecret.enabled AND fatsecret[flag]

  Master OFF => ALL features OFF (regardless of individual flags)
  Master ON  => each feature checks its own flag

Implementation Approach

Flags are stored in a React context provider, read via a useFeatureFlag('nutritionPanel') hook. Components conditionally render based on the hook return value. The full specification, including the operational runbook, emergency kill switch procedure, and rollout timeline, is in the feature flag spec document.

Degradation Philosophy

Five principles govern how every feature degrades:

30-Day Rollout Plan

Sprint Outputs

File Locations

Team Roles

From Design to Dev

The recommended sequence for the dev sprint:

1. Implement the feature flag provider and useFeatureFlag hook
2. Build FS-001 (Barcode Enrichment) and FS-006 (Category Inference) first
3. Add FS-002 (Food Search Autocomplete)
4. Add FS-003 (Nutrition Panel)
5. Add FS-005 (Nutrition Summary), which depends on FS-003 data
6. Add FS-004 (Dietary Preferences), which needs the allergen data pipeline
7. Build the Feature Flag Settings admin UI
8. Run the QA test checklist against all features in both states